A dye-sensitized solar cell developed by Gratzel, et al., from Switzerland in 1991 is a photoelectric chemical cell containing a semiconductor nanoparticle having titanium dioxide (TiO2) as a main component, a dye for absorbing the sun's rays, an electrolyte, and a platinum counter electrode (Nature, Vol. 353, p. 737, 1991), and has advantages in that a manufacturing cost is low as compared to a silicon solar cell, there is a transparent property in the cell, the flexible cell can be manufactured, and the cell is relatively less sensitive to environmental changes. The dye-sensitized solar cell and a known silicon solar cell by a p-n conjunction are different from each other in that an absorption process of solar energy and a process of separating electron-hole couples to form a current flow are performed simultaneously in the known solar cell, but, in the dye-sensitized solar cell, the absorption process of solar energy and a charge transfer process are separated, solar energy is absorbed by using a dye, and the charge is transferred in an electron form by using a semiconductor.
The dye-sensitized solar cell attracts attention as a new regeneration energy source having a current power generation cost level because environmentally harmless materials are used and a manufacturing cost is ⅕ of that of a silicon solar cell. Even though the dye-sensitized solar cell has many aforementioned advantages, commercialization of the dye-sensitized solar cell has significant problems in view of long term stability and toxicity due to liquid leakage of the electrolyte solution and vaporization of the solvent when the solar cell is operated over a long period of time. The reason is because the electrolyte that has been used in the dye-sensitized solar cell includes a liquid volatile organic solvent such as acetonitrile. Accordingly, there is a demand for developing a novel polymer electrolyte material solving the aforementioned problems and improving cell performance.
Examples of a known method of manufacturing a polymer electrolyte include a method of adding a polymer to liquid electrolyte to perform physical gelling (Korean Patent No. 10-0553337 and Korean Patent Laid-Open Publication No. 10-2009-0107861) and a method of adding a monomer or a reactive oligomer to liquid electrolyte to perform polymerization, thus implementing chemical gelling (Korean Patent Laid-Open Publication Nos. 2006-0118068 and 2007-0060960). The physically gelled polymer electrolyte has problems in that a phase separation phenomenon may occur between the polymer and the organic solvent over time and resistance of a charge transfer-reaction is increased at an interface between an electrode and an electrolyte due to insufficient adhesive force to a metal oxide layer to reduce current and efficiency properties. Meanwhile, in the case where the monomer or the oligomer is added to the liquid electrolyte to perform gelling by a polymerization or crosslinking reaction, there are problems in that there is a high possibility of compounds remaining such as an initiator and a crosslinking agent added during the crosslinking and polymerization reactions and voltage or current properties of the solar cell are reduced when the compounds remain in the electrolyte.